GlobalISel: add a G_PHI instruction to give phis a type.

They're another source of generic vregs, which are going to need a type on the
definition when we remove the register width from MachineRegisterInfo.

llvm-svn: 280412
diff --git a/llvm/lib/CodeGen/GlobalISel/MachineLegalizer.cpp b/llvm/lib/CodeGen/GlobalISel/MachineLegalizer.cpp
index cc3d4ec..5a15f65 100644
--- a/llvm/lib/CodeGen/GlobalISel/MachineLegalizer.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/MachineLegalizer.cpp
@@ -30,8 +30,10 @@
   DefaultActions[TargetOpcode::G_ANYEXT] = Legal;
   DefaultActions[TargetOpcode::G_TRUNC] = Legal;
 
-  // G_TYPE is essentially an annotated COPY so it's always legal.
+  // G_TYPE and G_PHI are essentially an annotated COPY/PHI instructions so
+  // they're always legal.
   DefaultActions[TargetOpcode::G_TYPE] = Legal;
+  DefaultActions[TargetOpcode::G_PHI] = Legal;
 
   DefaultActions[TargetOpcode::G_INTRINSIC] = Legal;
   DefaultActions[TargetOpcode::G_INTRINSIC_W_SIDE_EFFECTS] = Legal;